Field
Example aspects described herein relate generally to communication network design, and more particularly, to a system, apparatus, procedure, and computer program product for evaluating a network.
Description of Related Art
In order to provide maximum use of communication networks at minimum cost, networks are typically planned based on three types of information:    (1) information regarding network elements (nodes) containing relevant telecommunications equipment, (2) information regarding links between the nodes, and (3) information regarding the volume (e.g., as indicated by an amount of bandwidth) and path(s) (active and/or protection) of each traffic flow.
In transport networks, these types of information are known and are the basis for planning new networks and growing existing networks. Transport traffic is circuit-based and consists of traffic flows that are defined along a path that, by design, remains unchanged and thus does not experience congestion. That is, transport traffic is provisioned by the service provider (e.g., a network operator) between end-points, and remains static until either a protection event occurs or the traffic is changed by the service provider. Traffic flows and volumes remain static in capacity and routing for long periods of time, months or years.
Traffic flows that are static in terms of volume and route have several benefits, such as a tendency not to become congested and not to be re-routed. Protection paths are provisioned and are not used for other traffic. Additional traffic can be added to an existing network without concern for affecting existing traffic. In short, with transport networks, the network behavior and traffic flows are predictable.
In contrast, Internet Protocol (IP) networks are self-organizing networks and are therefore not as predictable. Flows in IP networks are not provisioned by service providers. In IP networks, end users choose a source and a destination for traffic, and IP routers route the traffic from the source to the destination. The service provider typically does not know the individual traffic flows in terms of volume or route. Further, IP traffic flows may not be not long-lived and may last as short as seconds or minutes. There are also no mechanisms to prevent traffic from overloading a particular link or router. In cases where this happens, the routers may change the path for particular flows. However, this inherent protection scheme for IP traffic does not choose pre-defined routes, so any capacity that a network planner may have allotted for protection traffic, may not actually be used for protection traffic.
For IP networks, traffic can become congested, traffic can re-route, allotted protection paths can be used for other traffic, and new traffic cannot be added to the network without concern for affecting existing traffic. This creates difficulty for network planners and network operators. Congestion may occur at any time and in some cases may occur at regular times of the day. For example, enterprise traffic may be prevalent during daylight hours while a higher volume of entertainment traffic may occur in the evening, thereby causing daily shifts in traffic flows. Traffic flows can also be impacted by events, such as weather events that disable links or human events like sporting events or political events that can give rise to a change in traffic patterns.
Current approaches to planning IP networks are based on the determination of an aggregate amount of traffic passing through each link of a network. Use of the links is adjusted by using weightings in the routing scheme, such as a scheme called Open Shortest Path First (OSPF). However, this approach often does not sufficiently account for the unpredictable and changing traffic flows in an IP network.